Re: Driving TN5250 non-interactively

You say that the iSeries is on a private LAN.  Why not just write a 
program using ODBC to access the data you are after? Or, create some 
stored procedures on the iSeries and use a web service over there. I 
wonder if the direction is coming from someone that does not realize 
those facilities are available on that machine, or alternatively you 
don't have the ability to sign on and create things there.  If the goal 
is to run specific commands, you might consider an FTP script using 
"syscmd".

That said creating a screen scraper application really is all about 
knowing the 5250 data stream.

Try this for more understanding.  I pulled it from V5R3 since you said 
"iSeries" guessing that the system might be a bit further back in OS 
than current. 
http://publib.boulder.ibm.com/infocenter/iseries/v5r3/index.jsp?topic=/apis/dsm1f.htm

Jim Oberholtzer
CEO/Chief Technical Architect
Agile Technology Architects, LLC


On 7/15/2010 5:47 PM, Richard Nolde wrote:
> *This message was transferred with a trial version of CommuniGate(r) Pro*
> TN5250 list members:
>
> I've been tasked with writing an interface between an application that
> runs on a remote iSeries host, accessible with TN5250 over a private
> network, and our application that would query the iSeries in real time
> without human interaction. My application will run on a Linux or AIX
> box, and act like a broker between the local application and the remote
> iSeries host application that contains the database we are querying.
>
> I've been studying the current TN5250 source code to get a feel for what
> I'm up against and clearly this is no simple task. Can anyone recommend
> one or more books/online sources about how the TN5250 interface on
> iSeries works. eg format fields, data types, etc. I can generate the
> requests manually with TN5250 and get the desired results back as a
> spool file with lp5250d, so my main objective is how to replace the
> curses interface with one that reads from a file or other
> non-interactive source. Eventually, I will provide a daemon that handles
> requests from multiple clients over a socket interface and serializes
> them for submission to the iSeries host, but that isn't necessary for now.
>
>   From what I've read and seen by playing with the remote application, I
> will need to know the position, length, and data types for each field of
> each screen that I wish to use, and Action or Function Key definitions
> for each screen. Assuming I can build a map that identifies each
> component of each screen, and the sequence of screens that will be
> encountered, I would then load each field with the appropriate value and
> call one of the TN5250 functions to send the data on the stream to the
> remote host application.  If the application screen produces output, I
> may or may not chose to parse it directly if I can get everything I want
> from the print spool that is returned via lp5250d.  In the sample cases
> that I have looked at, the screen output simulates bold printing by
> issuing a carriage return and then resending the data for selected
> fields a second time, as might have been done with ancient line printers
> of yore. I can probably parse this out but it would be nice to be able
> to disable this altogether.  I'm currently not using a Host Print
> Transform on the print spool output, only scs2ascii as there are no
> graphics involved. The returned data is in a format that I should be
> able to parse on my end as long as I know the parameters that were used
> to generate the query and the screen from which the output is derived.
>
> I note that the TN5250 application can be compiled without ncurses
> support, but doing so produced an executable that will not interact with
> the remote host. I assume that this is due to the field position
> requirements of the remote application.
>
> My initial approach is to build a profile of all the function calls in
> the tn5250 interactive application and see which ones call functions
> from the ncurses library. Once I understand how/where the screen
> co-ordinates are being set/read, I may be able to write a function that
> will read the appropriate values from my template files and the input
> data stream.
>
> Any ideas/suggestions and online documentation references would be
> welcome.  I have no access to the iSeries host except through the remote
> application. My servers run Linux or AIX 5.3.
>
> Thanks,
> Richard Nolde
>    
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